Malnutrition and wasting are common in patients with renal failure; several factors may contribute to these problems. Continuous ambulatory peritoneal dialysis (CAPD) is a new and rapidly growing form of maintenance dialysis. Metabolic balance studies and clinical experiences attest to the anabolic effects of CAPD. The metabolic effects of CAPD may be due to extra calories derived from glucose absorption from dialysate, the steady-state biochemical and hemodynamic parameters, increased removal of toxins in the molecular weight range of 400-2000 daltons and/or a differing hormonal set. A major objective of this study is to identify and delineate the metabolic and nutritional differences between CAPD and either hemodialysis or the non-treated uremic state. Several metabolic, nutritional and hormonal factors will be evaluated under rigid metabolic conditions in the same patient as he undergoes CAPD and hemodialysis. The role of the high energy intake will be evaluated by studying the patient while he ingests three different caloric intakes. The possible role of various hormonal factors, (insulin, glucagon, somatomedin, epinephrine, PTH) known to be abnormal in uremia and possibly improved during CAPD, will be evaluated. Objective studies of the uremic syndrome itself will include evaluation of central nervous system function and muscle membrane potential. Such studies may have important consequences regarding the pathogenesis of uremia per se.